Bi-polar electrochemical cell



Nov. 22, 1966 y F. H. HORNE x-:TAL 3,287,251

BI-POLAR ELECTROCHEMICAL CELL Filed April 2, 1962 United States Patent O3,287,251 BI-POLAR ELECTROCHEMICAL CELL Frederick H. Horne, 541Prospect, Lake Bluff, Ill., and Robert Blevitzky, Evanston, Ill.; saidBlevtzky assignmto said Horne Filed Apr. 2, 1962, Ser. No. 184,355 5Claims. (Cl. 204-270) The invention is directed to an improved bi-polarelectrochemical cell for fluid electrolysis involving simultaneousproduction of ya liquid product and a gaseous product. Moreparticularly, the invention provides an unusually ellicient means ttorelectrolysis of uids at atmospheric pressure, under vacuum or underpressure, and simultaneous removal and separation of gases formed in orbrought into the cell, by causing fluid to pass through the cell which,acting on the uid, forms a liquid product and gaseous product inseparate form .and in high purity.

Another object orf the invention is to provide an electrolytic cell`apparatus to process all or part of a fluid stream under pressure orvacuum in a conduit by means of interposing the cell in the path of saidstream, or by means of admitting a portion of the uid to the cell andreturning the cell liquid product to the conduit, and venting the gasesformed or brought into the cell to the atmosphere or to a suitable gascontainer or to said conduit.

Another object of the invention i-s to provide an apparatus of simple,compact modular construction which is readily and economically adaptableto various electromechanical processes and Various electric currentsupplies and potentials.

Another object is to provide an apparatus to increase the current, powerand material eiciency of an electrochemical process by increasing theapparent density of the uid undergoing electrolysis, through removal ofthe gaseous products from each cell chamber and returning de-entrainediluid to said cell chamber.

A further object of the invention is to provide a lai-polar cellapparatus which is adaptable for electromechanical processing ofnoxious, poisonous, corrosive or radioactive fluid or lluids becomingnoxious, corrosive or poisonous or radioactive when processedelectrochemically.

A further object of the invention is to provide an electrolytic cellapparatus which may be fixed or portable and which is adaptable forattachment yto a pressurized conduit handling a fluid containing forexample, lsoluble halides, and electrolyzing such halides to producehypohalites or halates.

Many other objects and advantages will be apparent to those xskilled inthe art from the disclosure herein given.

In one application of this invention, using a pressurized sodiumchloride solution of approximately 5% by weight, we have producedlsodium hypochlorite solutions at 75 p.s.i. bearing about 2% by weightavailable chlorine and less than 50 parts per million sodium chlorate,and using a total potential of 117 volts direct current of 21/2 amperes,and using electrodes of the character described in our copendingapplication. Hydrogen gas formed in the bipolar cell was produced freeof entrained electrolyte and was safely vented to the atmosphere.

In another application orf our invention, by using a pressurized saltpot feeder, We were able to chlorinate a stream of water toconcentrations of 0.1 -to 500 parts per million using a variable voltagesource. The apparatus also may be attached and used effectively for themethod described in Ferris Patent No. 2,873,23 6, issued May 10, 1951.

The invention may be employed eectively in an electrochemical processrequiring the use of different anode and cathode material as in sodiumchlorate production,

,. ICC

by using iron cathodes and graphite anodes of the character described inour copending application.

In the drawings, wherein like reference characters indicate like orcorresponding part-s:

FIG. l is a perspective view 0f a unit or assembly embodying ourinvention.

FIG. 2 is a sectional view taken4 approximately on the line 2 2 of FIG.3;

FIG. 3 is a sectional view taken approximately on the line 3 3 of FIG.2;

FIG. 4 is a sectional view of a single cell element taken approximatelyon lthe line 4 4 of FIG. 3;

FIG. 5 is a sectional view taken approximately on the line 5 5 of FIG.2; and

FIG. 6 is a [sectional View taken approximately on the line 6 6 of FIG.2.

In general, the apparatus is of modular construction, comprising a bodyor housing structure rformed from a plurality of plate-like elements 1,suitably stacked or assembled with respective end elements 2 and 3 andsecured in assembled relation between respective compression plates 4and 5, by connecting bolts 6 and cooperable nuts 7.

Extending through openings in the respective compression plates 4 and 5and operably secured to the adjacent end elements 2 and 3 are respectiveconduits 8 and 9, the conduit 8 being designated as a fluid inlet andthe conduit 9 as a iluid outlet. Also operatively connected to the endelement 2 is a conduit 11 for the discharge of liberated gas.

Each element 1, as illusrtated in FIGS. 2, 3, 4 and 6, is provided withrespective disc-like electrodes 12 and extending from the endmostelements 1 are respective terminals 12 and 14 operatively connected tothe associated electrode 13 lby means of which a source of electriccurrent may be operatively connected to the assembly.

Each element 1, as illustrated in FIGS. 3 and 4, and the end plates 2and 3 are formed from a suitable nonconductive material which preferablyis resistant to corrosion by fluids involved and depending upon thenature of the particular operation to be elTected, material such asconcrete, ceramic clays, thermo-setting or thermoplastic polymers,either virgin, lilled or laminated, and other molded or machineahlematerials may be employed.

As hereinafter discussed in details, electrolyte lluid is adapted to beadmitted to the unit through the conduit 8, passing into the adjacentcell formed by the end plate 2 and adjacent element 1 from which the uidpasses to the succeeding cells through openings 15 in each electrode 12,and finally discharged from the conduit 9. As a result of the connectionof a source of current to the terminals 13 and 14, current will flowbetween the electrodes to partially electrolyze the luid in the cellcavities and any gas formed during such electrolysis will be suitablycol-- lected and discharged through the conduit 11.

In assembly of the apparatus a suitable number of elements 1 are coupledwith interposed gaskets 16 and to form a bi-polar cell apparatus ofsuitable predetermined voltage drop .and electrolyte conversioncapacity. In operation of our invention electrolyte flowing through thecell cavity is thus subjected to a direct current and gases duringelectrolysis, and any entrained electrolyte forming a froth, is carriedupward through suitable froth inlet ports 17. The gas-liquid mixtureimpinges on bailles 1S and 19 causing separation into a gaseouscomponent which ows out via gas port 21, and a liquid component which returns via electrolyte return port 22 and return groove 23 to the cellcavity at 24.

Ribs 25 Iserve the dual purpose of guiding the 'froth llow andstrengthening the tcell element. Each cell section is vsuitably sealedto the subsequent section by means 3 of the gasket 16 which is insertedin cooperable grooves 26.

FIG. 5 illustrates the end element or plate 3 of the apparatus to whichconduits 9 and 11 are connected. Fluid ports 27 and conduit 9 permitflow of electrolyte, with gas port 21 communicating with conduit 11.Gasket groove 11 is olf identical configuration as in cell element 4 ofFIG. 2 and permits sealing ofl` of the cell assembly. The end element 2is of corresponding construction, either omitting the port 21 or havingthe same plugged.

FIG. 4 illustrates the details of the construction of the electricalterminals 13 and 14. More specifically each terminal is attached to thefirst or the last electrode 12 of the apparatus by means of terminalbolt 28 which screws into the wall of the associated cell element andthence into the electrode 12 to make an electrical contact. A liquidtight seal is maintained by using seal gasket 29, bushing 31, gasket 32,washer 33 and compression nut 34 which compresses the gaskets 29 and 32in a pressure tight manner, thus preventing leakage of uid along thethreads of bolt 28. The remainder of bolt 28 is sufficiently long topermit attachment of an electrical cable lug 3S by means of washer 36and nut 37. In the attachment of bolt 28 to the electrode 12, it may bedesirable that the leading edges of the bolt 28 be self-tapping orfluted to assist in establishing good electrical contact with theelectrode 12.

Referring to FIG. 2, electrolyte enters the cell cavity via conduit 8and port 15 in the first electrode 12. The liquid then passes downwardthrough the cell cavity, through the electrode port 15 in the adjacentelectrode 12. and into the next cell cavity bounded by bi-polarelectrode 12 on the left. The vertically reversing ow continues to thelast cavity and out through outlet conduit 9.

To secure eflicient cell operation, froth formed in the cell cavitiesduring electrolysis should be removed. This removal or separation isfacilitated by the bailles 18 and 19, which, with the webs 17 and thechannel or grooves 23, form a de-entrainment section in the upperportion of each cell element. De-entrainment proceeds by means ofimpingement of the froth on the batiles and by means of contact of thefroth with separated liquid. Separated electrolyte liquid is returnedthrough ports 24 to the cell cavity from whence it came without dilutionwith liquid from different cell cavities. Removal of froth andaccumulating gases from the cell cavity increases the bulk density ofthe electrolyte in the cavity and increases electrolyte conductivitywhich in turn increases the overall cell voltage efiiciency and powereficiency.

Separated gas passes through ports 21 in cell element 1 and thence outthrough port 21 and conduit 11. Also by means of rapid and efficientseparation of electrolyte from the froth and return of such electrolyteto the cell cavity, maximum electrolytic conversion of the electrolyteentering the apparatus is realized. Such return is effected by means ofthe hydrostatic head of the separated electrolyte just above return port22, illustrated in FIG. 3.

Each bi-polar electrode 12, containing port 15, preferably rests againsta gasket 38 with sufficient pressure to maintain a seal equal to orgreater than the dynamic pressure drop from cell cavity to cell cavity.Electrodes may be of metal, non-metals, impregnated or coatednonmetallic materials. It will be understood by those skilled in the artfrom the compressibility of gasket 38 and the thicknesses of electrodes12 will be governed in part by cell operating pressures and electrodestrength.

As electrolyte passes through the apparatus it is discretely convertedin part in each cell cavity C until it reaches the last or outlet cavity3 formed by the last cell element 1 and adjacent element 3. By means ofaddition or subtraction of cell elements 1 and associated electrode 12,the parameter of voltage drop can be controlled at constant currentdensity, thus enabling operation of an electrochemical process at thehighest efficiency. The

modular construction of the cell elements also permits simple andeconomical manufacture of cells for widely varying voltage supplies.Only the rst and last electrodes 12 of the apparatus need be directlyconnected to the electric power supply. It is known, however, by thoseskilled in the art that the electrode may be ,connected in a seriesparallel bi-polar arrangement by addition of more terminals atintermediate electrodes of the apparatus and connection of terminals ina series parallel manner.

Each cell element 1 contains gasket grooves 26 on both faces and eachconduit connector or end element 2 and 3 contains gasket grooves on theliquid face. In assembling the apparatus embodying our invention,continuous O-ring or groove gaskets 16 are inserted in the grooves 26and each element and connector plate is placed in juxtaposition. Thesub-assembled apparatus is subsequently compressed with metalcompression plates 2 and 6 by tightening compression bolts 6 and nuts 7.Flat or full face gaskets may be substituted for groove gaskets 16 bysubstitution lof flat gasket faces on cell elements 1,`

and end elements 2 and 3. Non-metallic end or compression plates may beused for environments where metals are not desirable.

As previously mentioned, each electrode 12 is engaged with an associatedgasket 38 on the shoulder 39 of the cell element. sembly of theapparatus is sufliciently compressible so that the `outer surface of theelectrode 12 may be disposed `in the same plane as the vertical surfaceof the cell elements.

Electrodes 12 and the cell cavity portion of each cell element 1 arepreferentially cylindrical in shape for purposes of achieving highestmechanical strength; however, it is feasible and practical to userectangular, elliptical or other shapes. Certain electrodes arepreferred for specific electrochemical processes conducted in theapparatus described. For example, we have found that production ofhypohalite solutions is best carried out using graphite electrode onwhich platinum has been deposited.

Also, halate solutions are very efficiently produced in apparatusembodying our invention using a laminated platinum foil graphiteelectrode.

From the above description of our invention, it is seen that theinvention clearly provides means to efficiently electrolyze a fluidunder all conditions of pressure, tem-` perature, concentration, flowrate, voltage and current density, while automatically maintaining theelectrolyzing solution in the best state for the highest yield of` cellproduct coupled with high overall economy.

The invention also provides simple means for carrying out electrolysisof a uid in a bi-polar cell where noxious or harmful cell products orfluids must be completely sealed off from the ambient environment. Meansare also provided by the invention for froth separation in eachcompartment enabling operation at very high cell ow rates and highmaterial efficiencies.

Having thus described our invention, it will be obvious to those skilledin the art from the disclosure herein given that various immaterialmodifications may be made in the same without departing from the spiritof our invention; hence we do not Wish to be understood as limitingourselves to the exact form, construction, arrangement and combinationof parts herein shown and described or uses mentioned.

What we claim as new and desired to secure by Letters Patent is:

1. A bi-polar multi-cell electrochemical apparatus for fluidelectrolysis, comprising a housing having an inlet and an outlettherein, the housing being constructed to form a uid path operativelyconnecting said inlet and outlet for the passage of fluid through thehousing, a plurality of flat, substantially plate-like modular elementsrGasket 38 when compressed 'during as.`

including disc-like electrodes interposed in spaced relation in saidfluid path and forming a plurality of individual cells operativelyconnected in series, means for connecting the outermost electrodes to acurrent supply source, said housing constructed in the form of modularelements operatively disposed between spaced end elements, said modularelements each including a disc-like electrode provided with an openingcarried thereby through which the fluid for iluid electrolysis passes tothe succeeding cells through openings in each of said disc-likeelectrodes, each modular element provided with oppositely disposedsubstantially parallel end faces each adapted to abut an adjacentelement, said end faces being constructed to receive and cooperate withgasket means disposed between abutting end faces to eiect a fluid-tightseal therebetween, means operatively connected to each cell forwithdrawing liberated gas therefrom, said means for withdrawingliberated gas comprising a de-entraining chamber including baie meansassociated with each cell provided with a gas port and operativelycommunicating therewith for the separation of liberated gas from theliquid and oth, said housing provided with a uid passage therein foreach de-entraining chamber operatively communicating with liquid in suchcell to eiect a liquid return from said chamber to said liquid.

2. A bi-polar multi-cell electrochemical apparatus for uid electrolysis,comprising a housing having an inlet and an outlet therein, the housingbeing constructed to form a lluid path operatively connecting said inletand outlet for the passage of fluid through the housing, a

plurality of flat, substantially plate-like modular elements y includingdisc-like electrodes interposed in spaced relation in said uid path andforming a plurality of individual cells operatively connected in series,means for connecting the outermost electrodes to a current supplysource, said housing constructed in the form of modular elementsoperatively disposed between spaced end elements, said modular elementseach including a disc-like electrode provided With an opening throughwhich the uid for iiuid electrolysis passes to the succeeding cellsthrough openings in each of said disc-like electrodes, each modularelement provided with oppositely disposed substantially parallel endfaces each adapted to abut an adjacent element, said end faces beingconstructed to receive and cooperate with gasket means disposed betweenabutting end faces to elect a Huid-tight seal therebetween, meansoperatively connected to each cell for withdrawing liberated gastherefrom, said means for withdrawing liberated gas comprising ade-entraining chamber including baffle means associated with each cellprovided with a gas port and operatively communicating therewith so thatthe gas-liquid mixture impinging on the bafe means causes separationinto a gaseous component which flows out through a gas port provided ineach plate-like modulor element and operatively connected with each cellcavity formed by said spaced plate-like modular elements, and a liquidcomponent which returns by an electrolyte passage means provided with areturn port and a return groove to the cell cavity, each modular elementcompris-V ing a body member of a material that is relatively inert tothe iiuids with which it is to be employed, said body member havingsubstantially parallel end walls adapted to abut like end walls of likeadjustment cooperable body members, said body member having anannular-shaped portion, the inner periphery of which is provided with aninwardly extending shoulder, the associated disc-like electrode havingsubstantially parallel faces and of a configuration to be received inand supported by said annularshaped portion with one disc-like electrodeface disposed substantially in the plane of the adjacent end wall of thebody member and the other face inwardly spaced from the opposite endwall, operative with the adjacent modular element to define a cell spacetherein, and each body member provided with means including said bafilemeans and rib means providing froth inlet ports and integrally formedtherewith and cooperable with an adjacent body member similarly formedto provide the de-entraining chamber associated with each successivecell space operatively connected together.

3. A bi-polar multi-cell electrochemical apparatus for uid electrolysis,comprising a housing having an inlet and an outlet therein, the housingbeing constructed to form a iluid path operatively connecting said inletand outlet for the passage of fluid through the housing, a plurality offlat, substantially plate-like modular elements including disc-likeelectrodes interposed in spaced relation in said iiuid path and forminga plurality of individual cells operatively connected in series, meansfor connecting the outermost electrodes to a current supply source, saidhousing constructed in the form of modular elements operatively disposedbetween spaced end elements, said modular elements each including adisc-like electrode provided with an opening through which the lluid foruid electrolysis passes to the succeeding cells through openings in eachof said disc-like electrodes, each modular element provided withoppositely disposed substantially parallel end faces each adapted toabut an adjacent element, said end faces being constructed to receiveand cooperate with gasket means disposed between abutting end faces toeffect a fluid-tight seal therebetween, means operatively connected toeach cell for withdrawing liberated gas therefrom, said means forwithdrawing liberated gas comprising a de-entraining chamber includingbaille means associated with each cell provided with a gas port andoperatively communicating therewith so that the gas-liquid mixtureimpinging on the bae means causes separation into a gaseous componentwhich flows out through a gas port provided in each plate-like elementand operatively connected with each cell cavity formed by said spacedplate-like modular elements, and a liquid component which returns by anelectrolyte passage means provided with a return port and a returngroove to the cell cavity, each modular element comprising a body memberof a material that is relatively inert to the fluids with which it is tobe employed, said body member having substantially parallel end wallsadapted to abut like end walls of like adjustment cooperable bodymembers, said body member having an annular-shaped portion, the innerperiphery of which is provided with an inwardly extending shoulder, theassociated disc-like electrode having substantially parallel faces andof a configuration to be received in and supported by saidannular-shaped portion with one disclike electrode face disposedsubstantially in the plane of the adjacent end wall of the body memberand the other face inwardly spaced from the opposite end wall, operativewith the adjacent modular element to define a cell cavity therein, eachbody member provided with a portion adjacent the associated disc-likeelectrode cooperable when disposed adjacent a like portion of a similarmodular element to form the aforesaid de-entraining chamber operativelycommunicating with said cell cavity.

4. As an article of manufacture, a modular cell section for use in uidelectrolysis, comprising a plate-like element of a material that isrelatively inert to the fluids with which it is to be employed, saidplate-like element including substantially parallel end walls adapted toabut Y like end walls of similar plate-like elements, and formed with anannular-shaped portion, the inner periphery of which is provided with aninwardly extending shoulder, a disc-like electrode provided with anopening therein for the passage of fluid from one side of the electrodeto the other side thereof, said electrode being formed withsubstantially parallel faces and of a configuration to be received inand supported by said annular-shaped portion with one electrode facedisposed substantially in the plane of the adjacent end wall of theplate-like element and the other face inwardly spaced from the oppositeend wall, operative to form a cell space therebetween, said platelikeelement provided with a portion adjacent said disclike electrode andcooperable when disposed adjacent a like portion of a similar section toform a de-entrainment chamber operatively communicating with said cellspace, means carried by said plate-like element forming bales for saidde-entrainment chamber, and said plate-like element provided with apassageway therein and operatively connecting said de-entrainmentchamber with the cell space at a point spaced from the connectionthereof with said de-entrainment chamber for the return of uid from thelatter to said cell space, and the side walls of said plate-like elementprovided with respective grooves therein disposed adjacent theperipheral edges thereof and of a size to receive an endless gasketmember for effecting a seal between assembled cell sections.

5. As an article of manufacture, a modular cell section for use in Huidelectrolysis, comprising a plate-like element of a material that isrelatively inert to the fluids with which it is to be employed, saidplate-like element including substantially parallel end Walls adapted toabut like end walls of similar plate-like elements, and formed with anannular-shaped portion, the inner periphery of which is provided with aninwardly extending shoulder, a disc-like electrode provided with anopening therein for the passage of fluid from one side of the electrodeto the other side thereof, said electrode being formed withsubstantially parallel faces and of a configuration to be re ceived inand supported by said annular-shaped portion with one electrode facedisposed substantially in the plane of the adjacent end wall of theplate-like element and the other face inwardly spaced from the oppositeend wall, operative to form a cell space therebetween, said plate-likeelement provided with a portion adjacent said disc-like electrode andcooperable when disposed adjacent a like 'portion of a similar sectionto form a de-entrainment chamber operatively communicating with saidcell space, means carried by said plate-like element forming bales forsaid de-entrainment chamber, said plate-like element provided with apassageway therein and operatively connecting said de-entrainmentchamber with the cell spaced at a point spaced from the connectionthereof with said de-entrainment chamber for the return of fluid fromthe latter to said cell space, said plate-like element provided with anelectrical connecting terminal extending through the edge of saidplate-like element and in current conducting engagement with saiddisc-like electrode, and said terminal comprises an externally threadedmember threaded into said plate-like element and partially into saiddisc-like electrode.

References Cited by the Examiner UNITED STATES PATENTS 522,839 7/1894Knoer 204-268 892,983 7 1908 Digby 204-220 968,492 8/ 1910 McDorman204-268 1,292,024 1/ 1919 Niswonger et al 204-268 1,397,239 1 1/ 1921Slater 204-228 1,996,799 4/ 1935 Evans 204-275 2,191,574 2/ 1940 Martin204-238 2,862,864 12/ 1958 Berghaus 204--256 2,873,236 2/1959 Ferris204-95 FOREIGN PATENTS 28,353 12/ 1902 Great Britain.

400,247 10/ 1933 Great Britain.

745,048 2/ 1956 Great Britain.

202,238 4/ 1939 Switzerland.

JOHN H. MACK, Primary Examiner.

D. JORDAN, Assistant Examiner.

1. A BI-POLAR MULTI-CELL ELECTROCHEMICAL APPARATUS OR FLUIDELECTROLYSIS, COMPRISING A HOUSING HAVING AN INLET AND AN OUTLETTHEREIN, THE HOUSING BEING CONSTRUCTED TO FORM A FLUID PATH OPERATIVELYCONNECTING SAID INLET AND OUTLET FOR THE PASSAGE OF FLUID THROUGH THEHOUSING, A PLURALITY OF FLAT, SUBSTANTIALLY PLATE-LIKE MODULAR ELEMENTSINCLUDING DISC-LIKE ELECTRODES INTERPOSED IN SPACED RELATION IN SAIDFLUID PATH AND FORMING A PLURALITY OF INDIVIDUAL CELLS OPERATIVELYCONNECTED TO A CURRENT SUPPLY SOURCE, SAID THE OUTERMOST ELECTRODES TO ACURRENT SUPPLY SOURCE, SAID HOUSING CONSTRUCTED IN THE FORM OF MODULARELEMENTS OPERATIVELY DISPOSED BETWEEN SPACED END ELEMENTS, SAID MODULARELEMENTS EACH INCLUDING A DISC-LIKE ELECTRODE PROVIDED WITH AN OPENINGCARRIED THEREBY THROUGH WHICH THE FLUID FOR FLUID ELECTROLYSIS PASSES TOTHE SUCCEEDING CELLS THROUGH OPENINGS IN EACH OF SAID DISC-LIKEELECTRODES, EACH MODULAR ELEMENT PROVIDED WITH OPPOSITELY DISPOSEDSUBSTANTIALLY PARALLEL END FACES EACH ADAPTED TO ABUT AN ADJACENTELEMENT, SAID END FACES BEING CONSTRUCTED TO RECEIVE AND COOPERATE WITHGASKET MEANS DISPOSED BETWEEN ABUTTING END FACES TO EFFECT A FLUID-TIGHTSEAL THEREBETWEEN, MEANS OPERATIVELY CONNECTED TO EACH CELL FORWITHDRAWING LIBERATED GAS THEREFROM, SAID MEANS FOR WITHDRAWINGLIBERATED GAS COMPRISING A DE-ENTRAINING CHAMBER INCLUDING BAFFLE MEANSASSOCIATED WITH EACH CELL PROVIDED WITH A GAS PORT AND OPERATIVELYCOMMUNICATING THEREWITH FOR THE SEPARATION OF LIBERATED GAS FROM THELIQUID AND FROTH, SAID HOUSING PROVIDED WITH A FLUID PASSAGE THEREIN FOREACH DE-ENTRAINING CHAMBER OPERATIVELY COMMUNICATING WITH LIQUID IN SUCHCELL TO EFFECT A LIQUID RETURN FROM SAID CHAMBER TO SAID LIQUID.